|Georgi Guninski security advisory #42, 2001
Double clicking on innocent looking files may be dangerous
Windows Explorer, Internet Explorer - Windows 98, 2000 - when browsing
directories or shares
Date: 16 April 2001
This Advisory is Copyright (c) 2001 Georgi Guninski. You may distribute
You may not modify it and distribute it or distribute parts of it without
The information in this advisory is believed to be true based on experiments
though it may be false.
The opinions expressed in this advisory and program are my own and
not of any company.
The usual standard disclaimer applies, especially the fact that Georgi
is not liable for any damages caused by direct or indirect use
of the information
or functionality provided by this advisory or program.
Georgi Guninski bears no responsibility for content or misuse of this
advisory or program or
any derivatives thereof.
By double clicking from Window Explorer or Internet Explorer on filenames
extensions the user may be tricked to execute arbitrary programs.
If the file extension is certain CLSID e.g.:
then Windows explorer and IE do not show the CLSID and only the .txt
while the above file is in fact .hta file.
Some exploit scenarios include leaving such malicous files on shared
sending them in archive by email.
Workaround: Do not doubleclick from Windows Explorer or Internet Explorer
Microsoft was informed on 11 April 2001